Characterizing the Dosimetric Properties of MEH-PPV Using Thermoluminescence (TL)

2014 ◽  
Vol 1613 ◽  
pp. 127-131 ◽  
Author(s):  
Alejandro Ortiz-Morales ◽  
Ramón Gómez-Aguilar ◽  
Jaime Ortiz-Lopez ◽  
Epifanio Cruz-Zaragoza
Keyword(s):  
Conjugated Polymers ◽  
Kinetic Parameters ◽  
Dose Response ◽  
Glow Curve ◽  
Dose Range ◽  
Complex Structures ◽  
Order Model

ABSTRACTThe thermoluminiscent properties of MEH-PPV and MDMO-PPV conjugated polymers were studied in order to verify if they are suitable for use as TL dosimeter. The dose response that was analyzed cover the wide dose range 0.34-5.44 kGy. The measured glow curves show complex structures which were evaluated with kinetic parameters based on the MO (Mix Order) model together with the CGCD (Computerized Glow Curve Deconvolution) homemade program which is useful to understand the mechanisms responsible for TL emission.

A NEW THERMOLUMINESCENCE GENERAL ORDER GLOW CURVE FIT FUNCTION CONSIDERING THERMAL QUENCHING EFFECT

2019 ◽  
Vol 187 (1) ◽  
pp. 103-107
Author(s):  
S Harooni ◽  
M Zahedifar ◽  
E Sadeghi ◽  
Z Ahmadian
Keyword(s):  
Kinetic Parameters ◽  
Glow Curve ◽  
Thermal Quenching ◽  
Glow Peak ◽  
Heating Rates ◽  
Order Model ◽  
Quenching Effect ◽  
Fitting Procedure ◽  
Curve Fit ◽  
General Order

Abstract A new thermoluminescence (TL) general order glow curve fit function in terms of the intensity of peak maximum, Im and the peak temperature, Tm is presented in which thermal quenching (TQ) effect has been taken into account. Also, the conventional general order model and the new presented function were fitted to the glow peak 5 of LiF:Mg,Ti (TLD-100) and the kinetic parameters were obtained for different heating rates as the results of fitting procedure. It was found that increasing the heating rate, which makes the TQ more prominent, causes more divergence between the kinetic parameters extracted by applying two models. Considering that the TL intensity and the glow peak area reduce with shifting the glow peak to higher temperatures as a result of TQ, the new presented function gives more reliable results for the kinetic parameters.

Study of dosimetric characteristics of a commercial optically stimulated luminescence system

2017 ◽  
Vol 16 (4) ◽  
pp. 461-475 ◽  
Author(s):  
Gourav K. Jain ◽  
Arun Chougule ◽  
Ananth Kaliyamoorthy ◽  
Suresh K. Akula
Keyword(s):  
Dose Response ◽  
Response Curve ◽  
Light Exposure ◽  
Dose Range ◽  
Optically Stimulated Luminescence ◽  
Dose Response Curve ◽  
Field Size ◽  
In Vivo Dosimetry ◽  
Detector Response

AbstractBackgroundOptically stimulated luminescence dosimeters (OSLDs) have a number of advantages in radiation dosimetry making them an excellent dosimeter for in vivo dosimetry. The study aimed to study the dosimetric characteristics of a commercial optically stimulated luminescence (OSL) system by Landauer Inc., before using it for routine clinical practice for in vivo dosimetry in radiotherapy. Further, this study also aimed to investigate the cause of variability found in the literature in a few dosimetric parameters of carbon-doped aluminium oxide (Al2O3:C).Materials and methodsThe commercial OSLD system uses Al2O3:C nanoDotTM as an active radiation detector and InLightTM microStar® as a readout assembly. Inter-detector response, energy, dose rate, field size and depth dependency of the detector response were evaluated for all available clinical range of photon beam energies in radiotherapy.ResultsInter-detector variation in OSLD response was found within 3·44%. After single light exposure for the OSL readout, detector reading decreased by 0·29% per reading. The dose linearity was investigated between dose range 50–400 cGy. The dose response curve was found to be linear until 250 cGy, after this dose, the dose response curve was found to be supra-linear in nature. OSLD response was found to be energy independent for Co60 to 10 MV photon energies.ConclusionsThe cause of variability found in the literature for some dosimetric characteristics of Al2O3:C is due to the difference in general geometry, construction of dosimeter, geometric condition of irradiation, phantom material and geometry, beam energy. In addition, the irradiation history of detector used and difference in readout methodologies had varying degree of uncertainties in measurements. However, the large surface area of the detector placed in the phantom with sufficient build-up and backscatter irradiated perpendicularly to incident radiation in Co60 beam is a good method of choice for the calibration of a dosimeter. Understanding the OSLD response with all dosimetric parameters may help us in estimation of accurate dose delivered to patient during radiotherapy treatment.

Comparative study of kinetic parameters induced by different excitation sources: using a novel and user-friendly glow curve deconvolution spreadsheet

2018 ◽  
Vol 29 (18) ◽  
pp. 15732-15740 ◽  
Author(s):  
H. Durán-Muñoz ◽  
M. Hernández-Ortíz ◽  
C. Sifuentes-Gallardo ◽  
J. I. Galván-Tejeda ◽  
R. Sánchez-Zeferino ◽  
...  
Keyword(s):  
Comparative Study ◽  
Kinetic Parameters ◽  
Glow Curve ◽  
User Friendly

Background Levels and Radiation Dose Yield of o-Tyrosine in Chicken Meat

1991 ◽  
Vol 54 (12) ◽  
pp. 935-938 ◽  
Author(s):  
NOEMI CHUAQUI-OFFERMANNS ◽  
TOM MCDOUGALL
Keyword(s):  
Radiation Dose ◽  
Dose Response ◽  
Response Curve ◽  
Dose Range ◽  
Background Level ◽  
Chicken Meat ◽  
Dose Response Curve ◽  
Poultry Meat ◽  
Wet Weight ◽  
The Mean

The measurement of o-tyrosine levels in poultry meat is a potential method for postirradiation dosimetry of poultry. The validity of using o-tyrosine for this purpose has not yet been established. As part of the validation process, the o-tyrosine content in unirradiated chicken meat, the radiation dose response curve, and the effects of postirradiation storage on o-tyrosine levels are examined. In 18 individual samples, the mean background level of o-tyrosine was 0.18 ± 0.11 ppm (wet weight, 70% moisture), and the most frequent background level (60% of the cases) was between 0.05 and 0.15 ppm (wet weight, 70% moisture). In pooled samples of 10 chickens, the mean background level was 0.12 ± 0.03 ppm (wet weight, 70% moisture). The levels were not significantly affected by storage at 5°C (7 d) or by freezing the sample. The radiation dose response curve was linear within the dose range studied (0 to 10 kGy), with a slope of 0.127 ± 0.003 ppm (wet weight)/kGy. Although there was some variation in the intercept (0.132 ± 0.013), the slope was the same in all samples tested. Postirradiation storage at either 4 or 8°C until spoilage did not affect the levels of o-tyrosine. These data indicate that o-tyrosine level may be useful for determining the absorbed dose in chicken meat gamma-irradiated to doses greater than 0.6 kGy. Further validation studies are continuing.

In vivo biological response to recombinant interferon-gamma during a phase I dose-response trial in patients with metastatic melanoma.

1990 ◽  
Vol 8 (6) ◽  
pp. 1070-1082 ◽  
Author(s):  
J M Kirkwood ◽  
M S Ernstoff ◽  
T Trautman ◽  
G Hebert ◽  
Y Nishida ◽  
...  
Keyword(s):  
Interferon Gamma ◽  
Dose Response ◽  
Dose Range ◽  
Cell Subset ◽  
Optimal Dosage ◽  
Antitumor Effects ◽  
Ifn Gamma ◽  
Recombinant Interferon ◽  
Wide Range

Interferon-gamma (IFN gamma), as produced by recombinant DNA technology, has shown a wide range of immunomodulatory activity in vitro and in vivo. Clinical studies have attempted to establish a dose-response relationship to define optimal dosage ranges for induction of effector cell function and host response in patients with cancer. We conducted a randomized trial to test the in vivo biologic activity of five daily dosages ranging from 3 to 3,000 micrograms/m2, administered by daily 2-hour bolus injection or by continuous infusion for 14 days. We demonstrate comparable immunobiologic effects of recombinant IFN gamma (rIFN gamma; Biogen, Inc, Cambridge, MA) administered by these two schedules at the various dosages tested, and have defined a relationship of dose to biologic response over this 3-log10 dose range. Oligo 2'5' adenylate synthetase (2'5'As) induction, natural-killer (NK) cell activity, and T-cell subset distribution (heightened T helper/suppressor ratio) showed the most consistent treatment-associated changes and the greatest immunobiologic effects at dosages of 300 to 1,000 micrograms/m2. Mononuclear cell DR and DQ antigen expression showed no consistent dose-related treatment effect. The relevance of the phenotypic, functional, and enzymologic effects observed in this trial to any clinical antitumor effects of IFN gamma in cancer therapy must now be established.

Evidence for dose and dose rate effects in human and animal radiation studies

2018 ◽  
Vol 47 (3-4) ◽  
pp. 97-112 ◽  
Author(s):  
M.P. Little
Keyword(s):  
Dose Rate ◽  
Dose Response ◽  
Low Dose ◽  
Atomic Bomb ◽  
Dose Range ◽  
Quadratic Model ◽  
Linear Quadratic ◽  
Dose Rates ◽  
Atomic Bomb Survivors ◽  
Linear Quadratic Model

For stochastic effects such as cancer, linear-quadratic models of dose are often used to extrapolate from the experience of the Japanese atomic bomb survivors to estimate risks from low doses and low dose rates. The low dose extrapolation factor (LDEF), which consists of the ratio of the low dose slope (as derived via fitting a linear-quadratic model) to the slope of the straight line fitted to a specific dose range, is used to derive the degree of overestimation (if LDEF > 1) or underestimation (if LDEF < 1) of low dose risk by linear extrapolation from effects at higher doses. Likewise, a dose rate extrapolation factor (DREF) can be defined, consisting of the ratio of the low dose slopes at high and low dose rates. This paper reviews a variety of human and animal data for cancer and non-cancer endpoints to assess evidence for curvature in the dose response (i.e. LDEF) and modifications of the dose response by dose rate (i.e. DREF). The JANUS mouse data imply that LDEF is approximately 0.2–0.8 and DREF is approximately 1.2–2.3 for many tumours following gamma exposure, with corresponding figures of approximately 0.1–0.9 and 0.0–0.2 following neutron exposure. This paper also cursorily reviews human data which allow direct estimates of low dose and low dose rate risk.

scholarly journals Dose–Response of TLD-100 in the Dose Range Useful for Hypofractionated Radiotherapy

Dose-Response ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 155932581989408 ◽  
Author(s):  
Raffaele Liuzzi ◽  
Consiglia Piccolo ◽  
Vittoria D’Avino ◽  
Stefania Clemente ◽  
Caterina Oliviero ◽  
...  
Keyword(s):  
Dose Response ◽  
Radiation Treatment ◽  
Dose Range ◽  
Information Criterion ◽  
High Dose ◽  
Thermoluminescent Dosimeters ◽  
Dose Monitoring ◽  
Coefficients Of Variation ◽  
Best Fitting ◽  
Quadratic Models

Purpose: The aim of the study was to exploit the feasibility of thermoluminescent dosimeters (TLDs) in radiation therapy techniques in which high dose per fraction is involved. Methods: Dose–response of TLD-100 (LiF: Mg, Ti) was investigated in both 6-MV photon and 6-MeV electron beams. The element correction factor (ECF) generation method was applied to check the variability of the TLDs response. Two batches of 50 TLDs were divided into groups and exposed in the dose range 0 to 30 Gy. Regression analysis was performed with both linear and quadratic models. For each irradiation beam, the calibration curves were obtained in 3 dose range 0 to 8 Gy, 0 to 10 Gy, and 0 to 30 Gy. The best-fitting model was assessed by the Akaike Information Criterion test. Results: The ECF process resulted a useful tool to reduce the coefficients of variation from original values higher than 5% to about 3.5%, for all the batches exposed. The results confirm the linearity of dose–response curve below the dose level of 10 Gy for photon and electron beam and the supralinear trend above. Conclusion: The TLDs are suitable dosimeters for dose monitoring and verification in radiation treatment involving dose up to 30 Gy in a single fraction.

Sign in / Sign up

Export Citation Format

Share Document